June 28th, 2011
01:05 PM ET
If you are on dialysis like approximately 400,000 other Americans, then your life could change for the better in the next couple of years thanks to some new biomedical engineering.
The technology, announced this week at an American Heart Association conference on emerging technology, enables engineers to grow sheets of human cells in a laboratory, and then synthesize them into tubes, mimicking human blood vessels. Alternatively, the human cells, which come from skin cells, can be made into threads and then woven into the form of blood vessels.
The engineered blood vessels look especially promising to patients who need their blood filtered by hemodialysis, the most common type of dialysis. That process requires routinely puncturing a shunt with a large needle. Though the plastic shunts, which connect arterial blood to venous blood, wear out easily, this technology repairs itself, because it’s made of real human tissue.
The fundamental technology has been around for years, but only when a patient’s own skin cells were used in creating the engineered human tissue. That process takes about six months – too long for emergency situations – and comes at an enormous cost. This technology instead uses allogeneic skin cells, meaning they come from one “master” donor to create thousands of grafts which can be kept on the shelf under refrigeration for months and used in other people when needed.
To date, only three human patients have had the allogeneic blood vessel technology grafted into their bodies, but those results, the results from non-allogeneic blood vessel grafts, and pre-clinical trials have proven successful.
Todd McAllister, Ph.D., the CEO of the Cytograft Tissue Engineering, which creates this technology, says the human-tissue engineered vasculature will last approximately three years in patients – a big improvement over the life of plastic shunts which currently require multiple changes every year.
Other laboratories are working on similar technology, but Cytograft Tissue Engineering technology is the first and only, so far, to advance to human-clinical trials for a high-pressure arterial bypass model, meaning the grafts are strong enough to handle the pressures found in arterial blood vessels as opposed to low-pressure venous blood vessels.
There are many potential applications.
When an explosive device, like the improvised explosive devices (IED) afflicting so many U.S. service members, damages a limb, the most challenging part is not repairing the soft tissue of that limb, but repairing the vessels delivering blood to that soft tissue. With this technology, surgeons would be able to effectively replace the old blood vessels, thereby saving more tissue from amputation.
Another potential application of the technology is for coronary arterial bypass graft surgery, or heart bypass surgery. Each year about 300,000 people in the U.S. have the surgery which usually takes an artery or vein from elsewhere in the body and uses it to replaces a hardened vessel leading to or from the heart.
In children with congenital heart defects, surgeons often repair vessels with synthetic materials, which have to be replaced as the child grows, requiring additional procedures as the children matures. These engineered vessels have the potential to grow with the patient, reducing the number of additional surgeries.
According to McAllister, 2% of the entire Medicare budget is focused on just the problem of maintaining access shunts for hemodialysis, meaning any improvements in those shunts would result in significant cost savings.
The technology can be used to make a small stamp-sized patch or a large tubular vessel 30 or 40 inches long, which can be inserted via catheter for a minimally invasive surgery.
McAllister says he expects this technology to be in general use starting in 2013.
Cytograft Tissue Engineering’s manufacturing facilities are located in San Francisco, and the company conducts clinical research in Atlanta with Saint Joseph’s Translational Research Institute.
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